Distributed Generations (DGs) power sources are becoming more prevalent due to their advantages over central power generations. By harvesting energy from renewable energy sources, DGs can provide a sustainable solution for future power generation. In particular, solar energy can be harvested through Photovoltaic (PV) panels using PV inverters. PV inverters convert the DC power to an AC power compatible with the utility grid. In a distributed generation scheme, PV inverters should be able to integrate into the DG by reliably operating in the presence of other energy sources. Also, PV inverters should be able to operate in a grid-connected mode (on-grid) or in a stand-alone mode (off-grid) as a reliable power source. For instance, in a micro-grid scenario, the PV inverter should be able to perform in the presence of energy storage systems as well as in the presence of other energy sources such as a wind based generator or other forms of distributed power generators.
FIG. 1 shows a scenario where multiple energy sources are simultaneously operating with or without the presence of the utility grid. This figure shows an exemplary arrangement of the prior art for a micro-grid. In FIG. 1, the micro-grid includes PV panels, a wind turbine, and a generator as energy sources and a battery as an energy storage unit. The PV microinverters deliver the power from the PV panels to the micro-grid. In this system, intelligent circuit breakers are used to connect and disconnect the PV inverters from different components of the system. The intelligent circuit breakers are used to communicate with the PV microinverters in order to safely connect and disconnect different components of the micro-grid. One drawback of such a system is the requirement for a reliable communication system in order to safely synchronize different components of such a micro-grid. Another drawback is that, in many cases, the microinverters are not able to produce power on their own in the stand-alone mode due to the reactive power requirement of the local load.
The micro-grid in FIG. 1 requires several intelligent circuit breakers with a reliable communication. This increases the complexity and overall cost of the system. Also, in stand-alone mode, it is common for supervisory control to be required to perform the power management and to harmonize different components of the system. This supervisory controller needs to communicate with different local controllers in each component of the micro-grid, each of which could be in different physical locations. The architecture of this system is therefore not very reliable.
Based on the above, there is therefore a need for systems and devices which mitigate if not avoid the shortcomings of the prior art.